Study Finds Risk of Dementia Increases After Hypoglycemia

By RONI CARYN RABIN

23 april 2009--People with Type 2 diabetes may be at increased risk for developing dementia as they age, several studies have suggested. Now researchers say the higher odds may be linked to life-threatening drops in blood sugar, or hypoglycemia, usually caused by excess insulin.

A long-term study of thousands of older patients with Type 2 diabetes in Northern California found that those who had experienced even one episode of hypoglycemia serious enough to send them to a hospital were at higher risk for developing dementia than diabetic patients who had not experienced such an episode. With each additional episode, the risk of developing dementia increased, the study found.

The findings, to be published on Wednesday in the Journal of the American Medical Association, are significant given the high rates of Type 2 diabetes around the world, and the expectation that dementia rates will increase as the population ages.

“We’ve known for some time that patients with Type 2 diabetes are at greater risk of dementia and cognitive problems,” said Rachel A. Whitmer of the Division of Research at Kaiser Permanente in Oakland, Calif., one of the authors. “This adds to the evidence that balance of glycemic control is important, and that trying to aim for a very low glycemic target might not be beneficial and might even be harmful.”

The study found that the risk of dementia among patients who had experienced a single episode of hypoglycemia that required hospitalization was 26 percent higher than the risk for patients who had never had an episode.

Patients who had experienced two episodes faced an increased risk of 80 percent, while those who had experienced three episodes or more had a 94 percent increase in risk, or almost double the odds of developing dementia.

“To see an effect after just one episode is remarkable,” said Dr. Alan M. Jacobson, a researcher at the Joslin Diabetes Center in Boston. An earlier study of Type 1 diabetes and dementia found no connection, Dr. Jacobson noted.

Researchers gathered their data from 16,667 Kaiser Permanente patients with Type 2 diabetes. They used hospital data to determine how many had experienced severe hypoglycemic episodes from 1980 to 2002 and how many had first received a diagnosis of dementia from 2003 to 2007, when their mean age was 74 to 78.